reviewed by: Eskil Heyn Olsen <eskil@eazel.com>

* components/services/install/lib/eazel-install-logic2.c:
(add_to_dedupe_hash), (post_get_softcat_info),
(dedupe_foreach_depends), (check_if_related_package),
(check_tree_helper), (clean_up_dedupe_hash):
* components/services/install/lib/eazel-install-problem.c:
(get_detailed_messages_foreach):
Backport Eskil's dedupe changes to head, so we can build the
installer here. This fixes the "softcat is updating" bug (which
turned out to have nothing to do with softcat).